Non-cancerous tumours and conditions of the ovary

A non-cancerous (benign) tumour is a growth that does not spread (metastasize) to other parts of the body. A non-cancerous condition is a change to cells, but it isn't cancer. Both non-cancerous tumours and non-cancerous conditions can develop in 1 or both ovaries.

Non-cancerous tumours are not usually life-threatening. They are typically treated by surgery to remove all of the ovary or only the part that contains the tumour.Non-cancerous tumours don't usually come back (recur).

There are a few types of non-cancerous tumours of the ovary.

Benign epithelial tumours are the most common type of non-cancerous ovarian tumour. They start in the epithelial cells. These cells are found in the tissue (called epithelial tissue) that covers each ovary and lines the fallopian tubes and peritoneum.

The most common types of benign epithelial tumours include the following:

• Serous cystadenomas don’t usually cause symptoms when they are small. But they can grow to be very large and can cause symptoms such as pain, abdominal pressure or bloating.
• Mucinous cystadenomas are usually larger than serous cystadenomas. They typically only develop in 1 ovary, but sometimes are found in both. They can cause symptoms such as pain, feeling full quickly and nausea.
• Benign Brenner tumours are most often small tumours that don’t cause any symptoms. They are often found during a hysterectomy.

Benign stromal tumours start in cells that make up the supportive or connective tissue of the ovary (called the stroma). These tumours may make estrogen.

The most common types of benign stromal tumours include the following:

• Fibromas usually don’t cause symptoms. They sometimes cause abdominal pain or discomfort.
• Thecomas can cause symptoms such as breast tenderness as a result of making too much estrogen.

Benign germ cell tumours start from germ cells, which develop into eggs. Most benign germ cell tumours develop during the reproductive years.

The most common type of benign germ cell tumour is a mature teratoma (also called a dermoid cyst). It usually develops in 1 ovary, but can sometimes develop in both.

Non-cancerous conditions do not spread (metastasize) to other parts of the body and are not usually life-threatening.

There are a few types of non-cancerous conditions of the ovary.

Cysts are a common benign condition. A cyst is a fluid-filled sac that forms on the surface of, or inside, an ovary.

Most ovarian cysts are functional cysts, which means the ovary continues to work as normal with the cyst there. Functional cysts form during normal ovulation (release of the egg from the ovary). They can be small or large.

There are 2 types of functional ovarian cysts:

Follicular cysts form as the egg is developing in a follicle. A follicle is a small fluid-filled sac that contains an immature egg. Ovaries have thousands of follicles. During ovulation, a follicle will rupture (break open) and release its egg. A follicular cyst can form if a follicle doesn’t rupture.

Corpus luteum cysts develop on the corpus luteum, which is a collection of cells that form on the ovary temporarily after ovulation. Sometimes corpus luteum cysts bleed and cause the ovary to bulge or rupture. If a corpus luteum cyst ruptures, fluids escape into the abdomen. Larger corpus luteum are more likely to rupture than smaller ones.

Cysts can also form on or near the fallopian tubes. These are called paratubal cysts or paraovarian cysts. Paraovarian cyst cells can become cancerous, but this is rare.

Cysts may not cause symptoms. Larger cysts may cause abdominal pain or pressure. A ruptured corpus luteum cyst usually causes pain.

Most cysts go away after a few days or weeks. Sometimes they need to be removed with surgery.

During ovulation each month, an ovary releases an egg. But changes to the hormone cycle and ovulation process can affect the ovaries so that the eggs don’t mature and are not released. Instead, the eggs form very small cysts within the ovaries. This is called polycystic ovaries (“poly” means “many”). As cysts build up, the ovaries may get bigger and develop a thick outer layer.

Polycystic ovary syndrome (PCOS) is a common problem that can affect your hormones. Polycystic ovaries may be a sign of PCOS.

Polycystic ovaries and PCOS can cause irregular periods and make it harder to become pregnant. They may cause other signs and symptoms, such as weight gain, acne or hair growth on the face or body.

Treatment for polycystic ovaries and PCOS include:

• hormonal birth control to reduce symptoms and help regulate your period
• fertility medicines

The link between ovarian cancer and polycystic ovaries or PCOS is unclear. If you have PCOS, you're more likely to develop endometrial cancer than someone without PCOS.